Protein kinases constitute a large family of structurally related enzymes that are responsible for the control of a wide variety of signal transduction processes in the cell. They have been shown to be key regulators in most cellular functions including proliferation, cell metabolism, cell survival, apoptosis, DNA damage repair, cell motility . . . . Uncontrolled signalling due to defective control of protein phosphorylation has been implicated in a number of diseases, including, for example, cancer, inflammation, allergies, immune diseases, CNS disorders, angiogenesis . . . .
Amongst the families of protein kinases, one particular example is the Receptor-Interacting Serine/Threonine Kinases including RIP2. RIP2 (Receptor-Interacting Protein 2) is also referred to as Card-Containing Ice-Associated Kinase (CARDIAK), CARD3 (C-terminal CAspase-Recruitment Domain 3), Receptor-Interacting Protein Kinase 2 (RIPK2), or Rip-Like Interacting Clarp Kinase (RICK). RIP2 kinase is composed of an N-terminal kinase domain and a C-terminal caspase-recruitment domain (CARD) linked via an intermediate (IM) region (Curr. Med. Chem. (2005) 4, 35-42)). The CARD domain of RIP2 kinase mediates interaction with other CARD-containing proteins, such as the Nucleotide Oligomerization Domain Proteins, NOD1 and NOD2 (J. Biol. Chem. (2000) 275, 27823-27831 and EMBO reports (2001) 2, 736-742). NOD1 and NOD2 are cytoplasmic receptors which are activated by specific bacterial peptidoglycan motifs and play a key role in innate immune surveillance. Upon intracellular bacterial exposure, NOD1 or NOD2 binds to the protein kinase RIP2 to coordinate NF-κB (nuclear factor κ B)-mediated cytokine responses. Once associated with NOD1/2, RIP2 undergoes autophosphorylation on Tyr 474 (Y474), and acts as a molecular scaffold to bring together other kinases (TAK1, IKKα/β/γ) involved in NF-κB and MAPK activation (Nature Reviews Immunology (2006) 6, 9-20).
Both NOD1/2 and RIP2 are NF-κB regulated genes, and as such, their activation causes a positive feedback loop in which activation of NOD1/2:RIP2 stimulates further activation and further inflammation. Additionally, NOD1/2 and RIP2 expression are stimulated by a variety of mediators of inflammation, including TNF (Tumor Necrosis Factor) and IFN (Interferon). In addition to NF-κB pathway activation, the NOD1/2:RIP2 complex stimulates autophagy, bacteriocidal activity, MHC Class II presentation and MAPK (Mitogen-Activated Protein Kinase) activation. Overall, this pathway modulates the innate immune system to help tailor the adaptive immune response to eradicate the offending pathogen.
Dysregulation of RIP2-dependent signaling has been linked to autoinflammatory diseases. Patients with loss-of-function NOD2 alleles are prone to the development of Crohn's disease, an inflammatory disorder of the gastrointestinal tract (Am. J. Hum. Genet. (2002) 70, 845-857 and Microbes and Infection (2009) 11, 912-918). In contrast, gain-of-function NOD2 mutations have been genetically linked to other inflammatory diseases, such as Blau Syndrome/Early Onset Sarcoidosis (EOS), a pediatric granulomateous disease characterized by uveitis, dermatitis, and arthritis (Nature Genetics (2001) 29, 19-20 and Current Rheumatology Reports (2005) 7, 427-433). Mutations in NOD1 have been associated with asthma (Hum. Mol. Genet. (2005) 14, 935-941), and early-onset and extra-intestinal inflammatory bowel disease (Hum. Mol. Genet. (2005) 14, 1245-1250). Genetic and functional studies have also suggested a role for RIP2-dependent signaling in a variety of other granulomateous disorders, such as sarcoidosis (Journal of Clinical Immunology (2009) 29, 78-89) and Wegner's Granulomatosis (Diagnostic Pathology (2009) 4, 23).
The fact that both loss-of-function polymorphisms and gain-of-function mutations cause inflammatory diseases is likely due to the fact that NOD2 functions as a rheostat to help maintain normal immunologic homeostasis. Lack of coordination between inflammatory signaling pathways influences the development of inflammatory disorders, and the NOD1/2:RIP2 activation equilibrium is central to this coordination. Treatments for Crohn's disease and sarcoidosis currently rely on broad, non-specific immunologic inhibition (e.g., corticosteroids) or on specific cytokine inhibition (e.g., anti-TNF therapies) with significant costs and side effects. Treatment is less than ideal, however, because not all agents are equally efficacious, the diseases occur over long time frames, and not all agents remain efficacious in the same patient. The RIP2 Y474 autophosphorylation event has been shown to be necessary for effective NOD2 signaling and does not occur in the presence of the most common loss-of-function Crohn's disease-associated NOD2 allele. This autophosphorylation is inhibited by non highly selective kinase inhibitors, Gefitinib and Erlotinib, suggesting that RIP2's tyrosine kinase activity could be targeted specifically in the treatment of inflammatory diseases (Genes Dev. (2010) 1, 2666-77). Several clinical cases were reported about Gefitinib or Erlotinib treatment being efficient to clear psoriasis or reduce arthritic symptoms or insulin-resistant type 2 diabetes associated with metabolic syndrome (The Oncologist (2013) 18: e3-e5). In mouse established models of chronic inflammatory bowel diseases, inhibition of RIP2 activity by the small molecule SB203580 is efficacious to reduce induced-colitis (J Biol Chem. (2005) 15, 14981-14988.). None of these small molecules however, primarily and selectively targets RIP2. It was therefore an object of the present invention to provide a potent, selective, small molecule inhibitor of RIP2 kinase activity which can block specifically RIP2-dependent pro-inflammatory signaling and thereby provides a therapeutic benefit in autoinflammatory diseases characterized in increased and/or dysregulated RIP2 kinase activity.
We have now found that the macrocyclic pyrazolopyrimidines and imidazopyridazines and pharmaceutically acceptable compositions according to this invention are useful for the treatment of inflammatory disorders, in particular Crohn's disease, bowel disease, Sarcoidosis, psoriasis, rheumatoid arthritis, asthma and insulin-resistant type 2 diabetes, ulcerative colitis, lupus, uveitis, blau syndrome, granulomatous inflammation, in particular behget's disease, multiple sclerosis, and diseases associated with RIP2 kinase activity (i.e. RIP2-kinase associated diseases).